Screen printing processes are typically used to produce images on materials such as textiles and paper. Images can be produced by forcing colored liquids such as inks through a screen or mesh with a rubber blade. The type and consistency of the inks and substrate dictate the type and configuration of the mesh. Solvent-based inks, for example, can be printed with screens having a relatively low mesh count, which corresponds to the number of openings in the screen mesh per lineal inch. Conversely, other solutions such as UV-based inks can be screen printed through meshes having a relatively large mesh count. The pitch of a screen, or the distance between adjacent wires or threads in the mesh, is inversely related to the mesh count.
Accordingly, in processes involving the printing with more than one type of ink, it is often necessary to substitute screens between ink applications. For instance, a higher pitch screen may be used with a more viscous ink to print a first area of a sheet of cardstock with a graphic element, and a lower pitch mesh can be used with a less viscous ink to print text on a second area of the cardstock. Substituting the screens in this fashion expends can be quite time consuming. Moreover, it is often difficult to accurately align the substitute screen in perfect register with the first screen. The alignment process consumes further time and introduces the significant possibility of misalignment of the second printed image relative to the first.
Multiple-frame screen printing has been used to print multiple, different images with a single ink in a single pass. In those systems, however, there is no need to have the images printed by each frame be in register with one another. In fact, such registration generally cannot be achieved due to the fact that each frame is prepared separately and individually. Moreover, these systems have the same type of mesh in adjacent frames because only a single type of ink is used. Accordingly, these apparatus are not suitable for printing works wherein multiple images must be printed with different meshes yet remain in register.